From 6061f16a8a119a46e61f2ddbabdb58f83e8857f7 Mon Sep 17 00:00:00 2001

From: Paolo Bonzini <pbonzini@redhat.com>

Date: Fri, 25 Nov 2011 12:06:22 +0100

Subject: [PATCH 21/25] qiov: prevent double free or use-after-free

qemu_iovec_destroy does not clear the QEMUIOVector fully, and the data

could thus be used after free or freed again.  While I do not know any

example in the tree, I observed this using virtio-scsi (and SCSI

scatter/gather) when canceling DMA requests.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Signed-off-by: Kevin Wolf <kwolf@redhat.com>

---

 cutils.c |    3 +++

 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/cutils.c b/cutils.c

index 6db6304..24b3fe3 100644

--- a/cutils.c

+++ b/cutils.c

@@ -217,7 +217,10 @@ void qemu_iovec_destroy(QEMUIOVector *qiov)

 {

     assert(qiov->nalloc != -1);

+    qemu_iovec_reset(qiov);

     g_free(qiov->iov);

+    qiov->nalloc = 0;

+    qiov->iov = NULL;

 }

 void qemu_iovec_reset(QEMUIOVector *qiov)

-- 

1.7.7.5